JP2879997B2 - Load canceling device in drive unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load canceling device in a feed bar driving device of a transfer press, for example.

[0002]

2. Description of the Related Art Generally, in a transfer press machine, a cam mechanism is used to drive a feed bar.

When the feed bar is moved by the cam mechanism, as shown in FIG. 3, a swing lever 52 whose intermediate portion is rotatably supported by a support pin 51 is provided. At one end, a feed bar 54 is connected via a connecting member 53, and at the other end of the swing lever 52, a cam follower 56 that follows a driving cam body 55 is attached. A restraining cylinder device 57 for preventing the lever from moving away from 55 is connected to one end of the swing lever 52.

According to this structure, as shown in FIG. 4, a constant force, that is, at least a force larger than the maximum value (P) of the load (A) acting on the cam body 55, is always exerted by the restraining cylinder device 57. Are added, and the cam body 55
Has a drawback that the apparatus itself must be strengthened because an extra force is constantly applied.

By the way, in order to solve such a drawback, a force applied to the swing lever by the restraining cylinder device is applied to the cam body by applying a load in a direction opposite to a load acting on the cam body by the air cylinder. In order to reduce the size of the device itself by reducing the force acting on the device (see, for example, Japanese Patent Application No. 2-20627).

[0006]

According to the above conventional construction, an air cylinder is used to cancel the load acting on the cam body. However, there is a problem that the response is poor, and the hydraulic cylinder is used. In this case, when the feed bar or the like is operated at a high speed, there is a problem that vibration is generated at the time of hydraulic pressure switching and stable operating characteristics cannot be obtained.

Accordingly, an object of the present invention is to provide a load canceling device in a driving device that can solve the above problem.

[0008]

In order to solve the above-mentioned problems, a load canceling device in a driving device according to the present invention comprises:
The above-mentioned rocking lever of the driving device connected to the rocking lever which is rocked through the cam body to move the object is provided with a rocking lever.
Acting on the cam body and generating a load in the opposite direction to cancel an excessive load acting on the cam body, comprising: a hydraulic cylinder connected to the swing lever; A thrust detection that detects a difference in hydraulic pressure between a servo valve provided in the middle of a hydraulic pipe for supplying hydraulic pressure to the hydraulic cylinder and a rod-side cylinder chamber and a head-side cylinder chamber of the hydraulic cylinder and detects a thrust thereof. Means, a reverse load signal generating means for generating a reverse load signal in a direction opposite to the load acting on the cam body,
While Type comparing the reverse load signal from the detected thrust signal and the reverse load signal generating means by said thrust detection unit, the rocking lever together with eliminating the two signal difference
The reverse load signal so that the
A comparison means for outputting a control signal to the servo valve so as to be slightly larger than a force signal , and the rod-side cylinder chamber and the head-side cylinder chamber of the hydraulic cylinder are communicated via a bypass pipe. is there.

[0009]

According to the above construction, the swing lever is connected to the swing lever.
The hydraulic cylinder is used to drive the swing lever and the drive cam.
To cancel the excessive load
Since the swing lever is acted on the drive cam by the load, the cam
Can reduce excessive load acting on
Eliminates the need for a cancellation mechanism, so the entire system can be downsized.
You. Further, a rod-side cylinder chamber of the upper SL hydraulic cylinder and the head-side cylinder chamber, since communicated via the bypass pipe, it is possible to prevent the surging occurring during hydraulic switching, therefore also stable during high-speed operation Operating characteristics are obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, reference numeral 1 denotes a driving device for a feed bar (an example of an object) 2 in a transfer press, for example, in which an intermediate portion is swingably supported by a support pin 3 and one end is fed via a connecting member 4. An L-shaped swing lever 7 connected to the bar 2 and having a cam follower 6 following the driving cam body 5 attached to the other end.

[0011] Then, the swing lever 7 in the driving device 1, when moving the feed bar 2, the swing lever
-7 to the driving cam body 5 via the cam follower 6
A load canceling device 8 is provided for canceling an excessive load acting on the drive cam body 5 while acting on the load, that is, canceling out.

The load canceling device 8 supplies a hydraulic cylinder 11 which is connected to one end of the swinging lever 7 via two connecting links 9 and 10 and also serves as a restraining hydraulic cylinder 11. A hydraulic pressure difference between an electro-hydraulic servo valve (proportional control valve) 13 provided in the middle of the hydraulic pipe 12 and the rod-side cylinder chamber 11a and the head-side cylinder chamber 11b of the hydraulic cylinder 11 is detected to detect the difference. Thrust detecting means 14 for detecting thrust, reverse load signal generating means 15 for generating a reverse load signal in order to apply a load in the opposite direction to the load acting on the cam 5, enter the detected thrust signal is compared by a reverse load signal and the thrust detection unit 14 from the signal generating means 15, to eliminate both of these signal difference, i.e. thrust Together to match the reverse load, swinging
The cam follower 7 of the lever 7 contacts the cam body 5 with a small load.
A differential amplifier (comparing means) 16 for outputting a control signal to the servo valve 13 so as to follow and contact the throttle valve 13;
The hydraulic cylinder 11 includes a bypass pipe 18 that communicates between the rod-side cylinder chamber 11a of the hydraulic cylinder 11 and the head-side cylinder chamber 11b.

The thrust detecting means 14 inputs pressure signals from the pressure detectors 21A and 21B for detecting the hydraulic pressure of each of the cylinder chambers 11a and 11b of the hydraulic cylinder 11, and pressure signals from the two pressure detectors 21A and 21B. A subtractor 22 that calculates the differential pressure and outputs the load pressure;
The arithmetic unit 23 receives the load pressure from the subtractor 22 and calculates the thrust of the hydraulic cylinder 11 by multiplying by the cross-sectional area of the cylinder chamber of the hydraulic cylinder 11.

The thrust calculated by the calculator 23 is input to the differential amplifier 16 and compared with a reverse load value output from the reverse load signal generator 15 as a reverse load signal.

A double rod type cylinder device is used as the hydraulic cylinder 11 so that the cross-sectional areas of the rod-side cylinder chamber 11a and the rod-side cylinder chamber 11b of the hydraulic cylinder 11 are equal.

In the above configuration, for example, the feed bar 2
Is moved in a predetermined direction via the cam body 5 and the swing lever 7, the cam follower 6 of the swing lever 7
A restraining force is applied by the hydraulic cylinder 11 in order to prevent the vehicle from coming off. At this time, the restraining force is applied to the load (shown by the solid line a in FIG. 2) in the opposite direction to the load acting on the cam body 5 when the feed bar 2 is moved (FIG. 2).
Dashed line b), that is, the load acting on the cam body 5 is canceled. The magnitude of the load in the opposite direction is slightly larger in absolute value than the load acting on the cam body 5, and the cam follower 6 provided on the swing lever 7 does not separate from the cam body 5. Is taken into account.

The servo valve 13 is actuated through a reverse load signal from the reverse load signal generating means 15 to generate a predetermined thrust. Is fed back, and a predetermined reverse load is always applied to the swing lever 7 via the differential amplifier 16.

When the feed bar 2 is moved at a high speed, the hydraulic pressure supplied to the hydraulic cylinder 11 is also frequently switched. At this time, the cylinder chambers 11a and 11b on both sides of the hydraulic cylinder 11 are interposed by the throttle valve 17. Since the hydraulic cylinder 11 is in communication with the bypass pipe 18 provided therein, the operating characteristic of the hydraulic cylinder 11 can have a damping effect,
Therefore, surging, that is, vibration occurring at the time of hydraulic pressure switching can be prevented without providing a surging tank, and stable operation characteristics can be obtained even during high-speed operation.

In the above embodiment, when detecting the thrust of the hydraulic cylinder, the difference between the hydraulic pressures of the cylinder chambers on both sides is determined, and the difference is multiplied by the sectional area of the cylinder chamber. Therefore, a double rod type cylinder device was used so that the cross-sectional areas of the cylinder chambers on both sides were equal.For example, while detecting the hydraulic pressure of each cylinder chamber, the cross-sectional area of each cylinder chamber was , The force generated in each cylinder chamber may be obtained, and the difference between the two forces may be obtained by calculation. In this case, a single rod type cylinder device can be used.

[0020]

As described above, according to the configuration of the present invention, the vibration
The hydraulic lever connected to the moving lever
Cancels excessive load acting on the drive cam
The swing lever on the drive cam with a small load.
To reduce the excessive load acting on the cam body.
Eliminates the need for a separate cancellation mechanism
Thus, the whole can be miniaturized. Further, since the rod-side cylinder chamber and the head-side cylinder chamber of the hydraulic cylinder are communicated via the bypass pipe, the operating characteristics of the hydraulic cylinder can have a damping effect. Vibration can be prevented without providing a surging tank,
Stable operation characteristics can be obtained even during high-speed operation.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a load canceling device according to an embodiment of the present invention.

FIG. 2 is a graph showing a load curve acting on a cam body in the embodiment.

FIG. 3 is a side view showing a schematic configuration of a conventional load canceling device.

FIG. 4 is a graph showing a load curve acting on a cam body in a conventional example.

[Explanation of symbols]

 Reference Signs List 1 drive device 2 feed bar 5 cam body 7 swing lever 8 load canceling device 11 hydraulic cylinder 11a rod side cylinder chamber 11b head side cylinder chamber 13 servo valve 14 thrust detecting means 15 reverse load signal generating means 17 throttle valve 18 bypass pipe

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-20627 (JP, A) JP-A-1-237030 (JP, A) JP-A-62-209266 (JP, A) JP-A-59-209 209432 (JP, A) JP 62-26848 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16H 25/16 B21D 43/05

Claims (1)

(57) [Claims] To claim 1 wherein said rocking lever driving device is connected to the swing lever is swung through a cam body moves the object, excessive acting the swing lever to the cam member causes to act on the cam body a reverse load cancellation device for generating a load, such as canceling the Do load, a hydraulic cylinder connected to said swing lever, a servo valve provided in the middle hydraulic pipe for supplying hydraulic pressure to the hydraulic cylinder A thrust detecting means for detecting a difference in hydraulic pressure between the rod-side cylinder chamber and the head-side cylinder chamber of the hydraulic cylinder to detect a thrust thereof; and a reverse load in a direction opposite to a load acting on the cam body. A reverse load signal generating means for generating a signal, a thrust signal detected by the thrust detecting means and a reverse load signal from the reverse load signal generating means are inputted and compared. Yuradore with eliminating both the signal difference
Reverse load signal so that the bar acts on the cam body with a small load
And a comparison means for outputting a control signal to the servo valve so as to be slightly larger than the thrust signal , and the rod-side cylinder chamber and the head-side cylinder chamber of the hydraulic cylinder are communicated via a bypass pipe. A load canceling device in a driving device, characterized in that: